1. Field of the Invention
The invention relates to a method of determining the number of light sources, and particularly to a method of determine the number of each kind of light sources of an illumination device.
2. Description of Related Art
There are many researches about using light emitting diode (LED) as an artificial light source for plant growth. And wavelength ranges of red, green and blue lights and a ratio of the three color lights which are suitable for plant growth have been obtained through experimentation. A most common ratio of red light to green light to blue light is 10:0:0, 9:0:1, 8:0:2, or 8:1:1, etc. According to LED as a light source for baby leaves production in an environmental controlled chamber (Proceedings of the 4th International Symposium on Machinery and Mechatronics for Agriculture and Biosystems Engineering, Proceedings of the 4th ISMAB), plants grow better when an artificial light source with a ratio of red light to green light to blue light is 9:0:1 or 8:0:2.
According to a research, the above ratio of red light to green light to blue light is a power ratio of each kind of light sources, and the power irradiating on plants relates to a photon number within a specific wavelength range. Generally, in the present market, the ratio of red light to green light to blue light is directly represented by the number of each kind of LEDs in related products. For example, if the ratio of red light to green light to blue light is 8:1:1, then a number ratio of red LEDs to green LEDs to blue LEDs is 8:1:1 accordingly.
TW Patent Publication No. 421994 discloses a pot for plant growth including an electrical rail, a plurality of lamps, and a power. The lamp further includes a plurality of red LEDs, green LEDs, and blue LEDs which are arranged randomly. Power is provided through the electrical rail for the lamp to use in planting. Besides, TW Patent Publication No. 421993 discloses a plant growth box having a lamp as well. The lamp includes a plurality of red LEDs, green LEDs, and blue LEDs which are arranged randomly.
However, the power ratio of each kind of light sources is represented by the number of each kind of color LEDs, such that plant growth is adversely affected.